A liquid crystal display panel is widely known in recent years as a display of a household electrical appliance such as a computer and a television device. The liquid crystal display panel has a configuration that a pair of substrates consisting of a thin film transistor (TFT) substrate and a color filter (CF) substrate are opposed attached to each other so as to be parallel to each other while having a given space therebetween, in which liquid crystals are sealed.
Generally, a plurality of TFTs, and pixel electrodes connected thereto are arranged in a matrix on the TFT array substrate. Meanwhile, color layers are arranged in a matrix on the CF substrate, and a common electrode is provided over the CF substrate. By varying a voltage applied to the electrodes, alignment of the liquid crystals can be controlled.
In producing the liquid crystal display panel described above, until the midway of the production process, processes of forming pixel electrodes and color layers for a plurality of liquid crystal display panels are performed on oversize mother substrates (oversize glass substrates for providing a plurality of liquid crystal display panels) while the mother substrates are yet to be divided.
Then, the mother substrates are attached to each other first to make an oversize panel, and then the panel is divided into a plurality of liquid crystal display panels. Alternatively, each of the mother substrates is divided first and then attached to each other to make a plurality of liquid crystal display panels (see FIGS. 11A and 11B).
A method for dividing the attached mother substrates as shown in FIG. 1A is used for providing miniature liquid crystal display panels used for mobile telephones or digital cameras. A method for attaching the divided mother substrates as shown in FIG. 1B is used for providing oversize liquid crystal display panels used for oversize liquid crystal televisions.
In these years, it is especially desired to achieve thin profiles and narrow frame regions of miniature liquid crystal display panels used for mobile telephones or digital cameras in order to achieve weight reduction and upsized screens of the panels. In this case, the thin profiles are achieved by achieving thin profiles of the substrates that make up liquid crystal display panels such as the above-described TFT substrates on which the pixel electrode are provided and the above-described CF substrates on which the color layers are provided. In addition, the narrow frame regions are achieved by widening the areas of display regions of the liquid crystal display panels, that is, by reducing the areas of the frame regions of the panels that surround the display regions.
PTL 1 indicated below discloses a technique concerning achieving a thin profile. To be specific, a TFT substrate assembly 200A that has a configuration such that portions to define display regions such as pixel electrodes for a plurality of liquid crystal display panels are arranged in a matrix on a mother substrate, and a CF substrate assembly 300A that has a configuration such that portions to define display regions such as color layers for a plurality of liquid crystal display panels are arranged in a matrix on a mother substrate are first attached to each other with seals 400 sandwiched therebetween so as to surround the display regions as shown in FIG. 12A. Then, liquid crystals 500 are provided in the display regions between the substrate assemblies 200A and 300A. Thus, a panel assembly (oversize panel) 100A is produced.
For example, in attaching the substrate assemblies 200A and 300A, the seals 400 having a frame shape that are made of a thermal hardening resin or an optical hardening resin are provided so as to surround the display regions of the CF substrate assembly 300A, and then the CF substrate assembly 300A and the TFT substrate assembly 200A are aligned opposed to each other in a vacuum chamber (not shown) to apply pressure to the substrate assemblies 200A and 300A under reduced pressure no higher than atmospheric pressure. Then, a process to put back the pressure in the vacuum chamber to atmospheric pressure, and a process to harden the seals 400 are performed.
Next, the panel assembly 100A is etched with the use of an etching liquid made of a fluorinated acid to achieve thin profiles of the substrate assemblies 200A and 300A as shown in FIG. 12B. In the etching, a process to soak the panel assembly 100A in the etching liquid stored in an etching bath (not shown) is performed.
Then, scribe grooves 200b and 300b used for division are formed on outer surfaces 200a and 300a of the substrate assemblies 200A and 300 respectively as shown in FIG. 12C. The scribe grooves 200b and 300b are formed by rotating a rotary blade of a cutter wheel (not shown) along lines for division, in this case, along regions where the seals 400 are disposed while pressing the rotary blade against the outer surfaces 200a and 300a. 
Then, by dividing the panel assembly 100A along the scribe grooves 200b and 300b, a plurality of liquid crystal display panels 100 are obtained as shown in FIG. 12D.
Thus, thin profiles of the substrate assemblies 200A and 300A can be achieved while the substrate assemblies 200A and 300A are still in the state of the panel assembly 100A and yet to be divided, which brings an advantage of improving production efficiency compared with the case of achieving thin profiles of the substrate assemblies 200A and 300A for each liquid crystal display panel 100 after division.